Direct injection is a common type of fuel injection system in which fuel is injected directly into the combustion chambers of an internal combustion engine cylinder by fuel injectors. The fuel injectors are connected to a fuel supply by a fuel rail, typically a tubular member The fuel injectors typically are mounted in fuel injector sockets in the fuel rail. Fuel rails in direct injection fuel systems are commonly mounted on the engine's cylinder head or engine block, with the fuel injectors also mounted on or resting on or in direct contact with the cylinder head or engine block.
A typical fuel injector has a nozzle which extends through the cylinder head for fluid communication with a combustion chamber. A seal is mounted on the nozzle and seals the nozzle against the cylinder head to block combustion gases. The seal moves with the nozzle in the event of movement between the nozzle and the cylinder head bore in which the nozzle is positioned. Such movement may be caused by vibrations of the fuel injector as will be described.
Direct injection fuel rails experience significantly higher fuel pressures than other types of fuel injection systems. High-pressure fuel pumps used in these systems commonly create pressure pulsations that can cause the fuel rail and the fuel injectors to pulsate or vibrate. This can cause wear and create undesirable noise, especially noticeable at idle speeds. Vibration also has been known to cause premature wearing of the injector seals between the injector nozzles and the cylinder head.
Forces originating from the structure of a fuel injector can also cause undesirable noise and wear. Energizing of the magnetic solenoid valve in the injector and the impact of the pin seating at injector closing can create a hammering effect which can cause component wear. Fuel injector noise can also be transmitted to the cylinder, and from there to other engine components such as the oil pan, front cover, cam cover, and intake manifold.
Attempts to alleviate noise and wear problems have included designs for suspending fuel injectors from the fuel rail, but such attempts have been complicated and not flexible enough to be used with various injector designs. A simple and flexible design for suspending a fuel injector from a fuel rail is needed which can support relatively high fuel pressure and combustion pressure loads.